allowSubmit = false;

function valAccountLogin() {
	
	formSrc				= document.f_AccountLogin;
	mailbox 			= formSrc.mailbox.value;
	pin 				= formSrc.pin.value;
	
	re 					= new RegExp("^[0-9]{4,6}$");
	
	if (mailbox == '') {
		alert("Please enter your mailbox number.");
	} else if (pin == '') {
		alert("Please enter your pin number.");
	} else if(mailbox.match(re)==null) {
		alert("Mailbox number can only contain 4 to 6 digits.");
	} else if(pin.match(re)==null) {
		alert("PIN can only contain 4 to 6 digits.");
	} else {
		allowSubmit = true;
		formSrc.submit();
	}
	
}